11/11/98
MDA GRANTEES DEVELOP NEW GENE THERAPY VECTORS
Muscular Dystrophy Association grantees Jeffrey Chamberlain and Giovanni Salvatori of the Department of Human Genetics at the University of Michigan in Ann Arbor report they have developed new and better versions of the so-called "gutted adenoviral vector" designed to deliver large therapeutic genes to muscle tissue. The findings were reported at the recent American Society for Human Genetics meeting in Denver.
The researchers say the new vectors (delivery vehicles) can carry the large dystrophin gene, which codes for the protein missing in Duchenne muscular dystrophy and abnormal in Becker muscular dystrophy, to muscle tissue in adult mice without triggering immune-system rejection. The dystrophin has lasted at least four months. Previous versions of the vector have caused an immune response that resulted in a loss of the transferred genes and the cells containing them over time.
A key difference is that the new vectors don't produce a protein known as "beta-galactosidase," used in experiments to easily mark which cells received the gene transfer. Until recently, scientists didn't realize that this marking protein was the cause of much of the immunologic reaction. The protein has no therapeutic function.
The scientists also say they have a new way of producing large quantities of the vectors that eliminates contamination by other proteins or viruses that could also trigger an immune response.
Chamberlain, a geneticist, and Jerry Mendell, a neurologist who co-directs MDA's clinic at Ohio State University in Columbus, say they hope to test the new vectors for their safety in humans next year.
Proof of the vectors' safety is a crucial step before trials of gene therapy in Duchenne or Becker muscular dystrophy can be undertaken.
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